My Projects

The Eleven Grooved Box – Tools

I am a big fan of Roy Underhill’s “The Woodwright’s Shop”. Last fall was the 32nd season, and he’s still wearing the same hat. The second episode was titled “The Eleven Grooved Box”, a project Roy uses in his woodworking school. You can see it here. I was attracted to this project because he uses Stanley 45 combination planes to make all eleven grooves. I have a Stanley 45 and have been looking for an appropriate project so I am trying to duplicate what Roy does as closely as I can.

You should watch the half hour video to see how Roy makes the box. I am going to document how I do it, and pass along some things I learned, and in particular, show how I made those #$%@! spline grooves. Each corner of the box has to have two matching grooves plowed for splines, without these the box would be very weak. You can see these in the corners of the lid in the photo. Cutting those spline grooves with an old Stanley 45 might be easy for Roy but for everyone else it’s a pain. A millisecond of inattention and the sides of the groove are ripped up. So like any self respecting woodworker, I made a jig.

My grooving jig for the Eleven Grooved Box

After almost giving up on this project, I sat down and analyzed what is happening. When plowing the grooves, you have to hold the plane perfectly perpendicular to the 45 degree mitered surface. The fence on the Stanley plane rides on the reference surface. But the skate is captured in the plowed groove! If you let the plane roll to the right, the fence lifts off the reference surface a bit and not much happens. But if you let the plane roll to the LEFT, the fence digs into the reference surface and pulls the blade to the left. The result is a horribly shredded edge on the left side of the groove. In the video, Roy has an Iron Arm and holds that Stanley perfectly aligned through the whole operation. My arm is made of rubber so I knew I had to make a jig to get the plane to behave.

V1.0 – My first jig attempt was a piece of 2×6 cut off at one end at 45 degrees, with a stop block attached. The stop block helps control tear out at the end of the cut and makes it easier to initially align the work piece with the plane. It did not help with the left side shredding problem, in fact made it worse.

First attempt at a jig for cutting spline grooves

V2.0 – Added a second 45 degree cut at the end of the 2×6, creating a 90 degree angle at the tip. That spaced the work piece farther away from the fence face. I reasoned that the longer roll radius would pull the blade over less if I let the plane drift off axis. It helped a little but still not satisfactory.

Second attempt at a spline groove jig

V3.0 The third revision adds a second reference surface for the BOTTOM of the plane fence.

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Third attempt at a spline groove jig

The fence is now constrained by hard surfaces in the down and right directions, and in the up and left directions by my left hand. It can only move back and forth like it’s supposed to. The whole thing gets clamped in a bench vise for the plowing operation, just like in the video.

The Stanley 45 in working position on the V3.0 jig. The fence is riding on two reference surfaces

The bottom reference surface is constructed at the rear of the jig by screwing on a 3/4 piece of scrap cut off at 45 degrees at the top. That 45 degree surface is 90 degrees from the fence reference surface of the jig. The two screws are in elongated slots so the added piece can be adjusted up or down, which in turn moves the small block of hard wood up and down the fence reference surface. I made a one time tweak so the plane is level and aligned with the work piece bevel at the beginning of the cut and tightened the screws.

Showing the jig with added fence bottom support

There is a small block of hard wood on which the plane fence actually rides, that sits loosely on top of the added piece.

The hardwood block in working position

The hardwood block has screws inserted in each end so it won’t slide off the jig when the plane is working.

Hardwood spacer block showing screws that keep it from sliding away

I start the cut with one light pass at the end so I can see where the plane is plowing, then knife down the grain like Roy does. With that, and the v3.0 jig I’m getting perfect spline grooves in the mitered surface.

An end piece with groove cut using the V3.0 jig

Stanley 45 tips for the Eleven Grooved Box

1. The eighth inch wide inch cutter needs to be as sharp as possible. I use one of the cheap “Eclipse Style” honing guides. I had to file the rounded jaw slightly to get it to grip the small cutter firmly. Use a simple wooden stop gauge to set the cutter for a 35 degree sharpen angle. Then the problem is, the narrow cutter can’t keep the gauge from wobbling during the honing process. The local hardware store had nylon bushings exactly the same diameter as the guide roller, with an ID the same as the guide screw shaft. I pulled the knob off the screw shaft and hacksawed a screwdriver slot across the end. With the knob removed, I can put a nylon bushing on each side of the guide and they act as outriggers to keep the whole thing true to the stone.

Modified honing guide with eighth inch cutter and outrigger wheels

To be really sharp, you have to flatten and polish the back side of the cutter as well. This is complicated by Stanley having made the 45 cutters slightly curved. You can use the Charlesworth ruler trick but you will need a thicker than usual ruler because of the curve. I found it good enough to just free hand polish the back by putting a lot of finger pressure on the tip.

2. Use a good ruler and measure the distance between the fence and the skate at front and back. Mine is typically wider at the rear, which causes the skate to bind in the groove. Loosen the fence rear lock screw and push it around until the measurements are the same.

3. Wax (Paraffin from a candle) the face of the fence, the bottom of the fence, the bottom and side of the skate.

4. Don’t overtighten the cutter lock bolt. It doesn’t take much to hold the eighth inch cutter in place.

5. Use an eighth inch drill bit to set the depth stop. When the groove is finished, lay the drill bit in the trench and if it sticks up above the beveled surface, back off the depth stop and cut a little more.

Glue up tips for the Eleven Grooved Box

1. Glueups have to be rehearsed. Make sure you can get the box assembled before the glue starts to grab.

2. I’m using Titebond III which has a little bit longer open time than Titebond II. I don’t have a Roy Underhill style glue pot.

3. Use an acid brush with the bristles cut off to about 3/8 inch to apply glue. Avoid applying a lot to the inside edge as squeeze out is difficult to remove there.

5. Apply glue to all the miters and grooves then wait a minute for that to soak into the end grain. Then apply another coat of glue and insert the splines. An easy way to apply glue to the splines is to lay a sheet of foil or waxed paper on the bench, make a puddle of glue, and roll the spline around in that.

Great job. I was trying some similar things, having failed to control tearout on the endgrain. One question is on the fence bottom support spacer. Does it not have to move 1/8″? Do you have to adjust the two screws every time? TIA

The spacer does not move. I have in fact, now permanently screwed it all together. It works because the blade is some distance from the fence. As the blade cuts deeper it goes through an arc with the center of the arc being the fence. Since the fence and blade are separated, the 1/8″ arc segment is shallow enough that it doesn’t cause a problem. In view of all this, the initial setting of the bottom support should be such that the blade is 1/16″ higher than level. Then when the groove is finished it will be 1/16″ lower than level. It does bind a bit and waxing the skate halfway through the cut helps a lot.